1. Technical Field
Embodiments of the present invention relate to a polymer, an electrode for a lithium secondary battery including the polymer, and a lithium secondary battery employing the electrode.
2. Related Art
Lithium secondary batteries have high voltage and high energy, and are therefore useful in a variety of applications. For example, electric vehicles (e.g., hybrid electric vehicles (HEVs) or plug-in hybrid electric vehicles (PHEVs)) need batteries capable of operating at high temperatures, being charged or discharged with a lot of electricity, and having a long lifetime between charges. Accordingly, electric vehicles require lithium secondary batteries with good discharge capacities and lifespan characteristics.
To improve the capacity and lifespan of lithium secondary batteries, the positive electrode and negative electrode materials, as well as the binder (which make up the lithium secondary battery) have been actively studied.
As a binder for a negative electrode of a lithium secondary battery, a mixture of sodium carboxymethyl cellulose (Na-CMC) and an aqueous dispersion of styrene-butadiene rubber (SBR) has been used. Na-CMC maintains the dispersibility of the active material and the stability of the slurry. The aqueous dispersion of SBR improves the flexibility of the electrode plate and the binding force of the active material layer with respect to the substrate. Accordingly, use of these materials has conventionally been considered important. However, SBR is non-conductive (i.e., it is not electrically conductive), and therefore acts as a resistor in the battery, thereby adversely affecting the lifespan of the battery.